Add a try-include word (which acts the same as "include") and use it to

conditionally include (but ignore failures) /boot/loader.rc.local and
/boot/menu.rc.local -- to make customizing the menu easier.

Reviewed by:	alfred
Discussed on:	-hackers

sys/boot/forth/loader.4th

@@ -233,7 +233,16 @@ include /boot/check-password.4th
   s" disable-module" s" disable loading of a module" .?
   s" toggle-module" s" toggle loading of a module" .?
   s" show-module" s" show module load data" .?
+  s" try-include" s" try to load/interpret files" .?
 ;
 
+: try-include ( -- ) \ see loader.4th(8)
+  ['] include ( -- xt ) \ get the execution token of `include'
+  catch ( xt -- exception# | 0 ) if \ failed
+    LF parse ( c -- s-addr/u ) 2drop \ advance >in to EOL (drop data)
+    \ ... prevents words unused by `include' from being interpreted
+  then
+; immediate \ interpret immediately for access to `source' (aka tib)
+
 only forth also
 

sys/boot/forth/loader.4th.8

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 17, 2013
+.Dd November 13, 2013
 .Dt LOADER.4TH 8
 .Os
 .Sh NAME
@@ -158,6 +158,13 @@ files to specify the action after a module loading fails.
 Used inside
 .Xr loader.conf 5
 files to specify the action after a module loading fails.
+.It Ic try-include Ar file Op Ar
+Process script files if they exist.
+Each file, in turn, is completely read into memory,
+and then each of its lines is passed to the command line interpreter.
+If any error is returned by the interpreter, the try-include
+command aborts immediately, without reading any other files, and
+silently returns without error.
 .El
 .Sh FILES
 .Bl -tag -width /boot/loader.4th -compact

sys/boot/forth/loader.rc

@@ -3,6 +3,7 @@
 \
 \ Includes additional commands
 include /boot/loader.4th
+try-include /boot/loader.rc.local
 
 \ Reads and processes loader.conf variables
 \ NOTE: Change to `initialize' if you enable the below boot menu

sys/boot/forth/menu.rc

@@ -120,6 +120,10 @@ set optionstoggled_ansi[6]="Verbose..... On"
 \ 
 set menu_timeout_command="boot"
 
+\ Include optional elements defined in a local file
+\ 
+try-include /boot/menu.rc.local
+
 \ Display the main menu (see `menu.4th')
 set menuset_initial=1
 menuset-loadinitial

sys/boot/i386/loader/loader.rc

@@ -3,6 +3,7 @@
 \
 \ Includes additional commands
 include /boot/loader.4th
+try-include /boot/loader.rc.local
 
 \ Reads and processes loader.conf variables
 initialize